A variable capacitor adopting micro-electromechanical systems (MEMS) technology is proposed. In such a capacitor, capacitance can be varied with a change in distance between two electrodes or interelectrode distance caused by changing the electrostatic attraction between the two electrodes. Specifically, the proposed variable capacitor can enter one of two states, one being an up-state which is relatively great in interelectrode distance and the other a down-state which is relatively small in interelectrode distance. A voltage produced by a charge pump circuit is applied between the two electrodes to change the capacitor from the up- to the down-state.
When a voltage produced by a charge pump circuit is applied between two electrodes of a variable capacitor, charge moves from the charge pump circuit to the variable capacitor, which may cause a problem of reduction in output voltage of the charge pump circuit or of increasing the time to switch from the up- to the down-state, impairing the switching operation of the variable capacitor.
Therefore, it is desired to provide an electronic device which is prevented from exerting a bad influence on the switching operation of a variable capacitor.